If all it took was that someone be reconciled to Rome to be legitimate then all NO priests and bishops would be legitimate, which we know is not the case.
To be legitimate demands matter, form, and intent in reception of sacraments in a legitimate Catholic lineage.
Since duarte-costa was excommunicated to the severest degree, it means they will never be welcomed back into the Church. So they started their own "catholic" church. The intent when ordaining or consecrating, therefore, could not be to join them to The true Catholic Church because they, themselves, are not part of it. You dont need to consider matter or form, even though those may be wrong, too.
Therefore, the duarte-costa "priests" and "bishops" would have to be re-ordained or re-consecrated correctly in a legitimate lineage before being legitimate themselves, which is what many from the duarte-costa line do.
To be "re-ordained" or "re-consecrated" is a sacrilege, and in and of itself incurs an excommunication. What I believe you are wanting to say is CONDITIONALLY ordained/consecrated.
The Catholic Church has always held that the Sacraments of schismatics are valid, provided that there is proper form, matter, intent, and a valid minister.
So, do Antiochian Orthodox priests who convert to the Catholic Faith require "re-ordination"? If so, can you you please provide examples of when the Melkite Greek Catholics were "re-ordained" upon returning to the True Faith from Antiochian Orthodoxy? The same should easily be found of the Armenians, Greeks, Ruthenians, Ukrainians, etc.
There are problems indeed with many in the Duarte-Costa lineage, just as with the Old Catholics and even some in the Thuc lineage. These problems stem from many claiming to have validly received Holy Orders in the lineages, when in fact it is simply a fantasy in one's own mind. This is a separate issue from "legitimacy" and "validity".